Access catheter and method for maintaining separation between a falloposcope and a tubal wall

ABSTRACT

A method and apparatus are provided for imaging a narrow body lumen, the method comprising maintaining separation between a distal end of an optical viewing scope and a lumen wall with a spacing structure which extends distally from the distal end of an access catheter. Optional spacing structures include distal cages and a guidewire which is fixed to and extends distally from the access catheter body. The invention is particularly beneficial during retrograde imaging of the fallopian tube, as it prevents the tubal wall from coming into such close proximity to a falloposcope as to produce &#34;white-out&#34; on the imaging monitor.

This is a Division of U.S. patent application Ser. No. 08/544,384, filedOct. 10, 1995, now U.S. Pat. No. 5,716,321 the disclosure of which isincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to endoscopic surgical methodsand apparatus. More particularly, the present invention provides anaccess catheter having a distally protruding structure which maintainsseparation between a viewing scope and a lumenal wall.

Diseases of the fallopian tubes are a major cause of infertility andtubal pregnancy. Until recently, diagnosis and treatment of tubaldisease has been hampered by the difficulty in accessing and imaging theinterior of the fallopian tube. Such difficulties, however, have beenlargely overcome by the recent availability of very small guidewires,catheters, and fiberoptic viewing scopes, usually referred to asfalloposcopes. Using these instruments and systems, a physician can gainatraumatic access to the interior of the fallopian tube through ahysteroscope positioned within the uterus. Such falloposcopic imagingtechniques were described by Kerin et al. in Fertil. Steril., Vol. 54,pp. 390-400 (1990), and in J. Laparoendoscopic Surg., Vol. 1, pp. 47-56.

Falloposcopic access and imaging techniques are generally performed asfollows. A hysteroscope is positioned within the uterus and anirrigating solution is introduced to distend the uterus and permit videomonitoring. A very small guidewire is then introduced through thehysteroscope and advanced past the ostium and into the fallopian tube.The guidewire will continue to be advanced until it approaches thedistal fimbria. A small tubular access catheter may then be advancedthrough the hysteroscope and over the guidewire into the fallopian tube,again preferably approaching the distal fimbria. After removing theguidewire, the falloposcope (which is a small diameter fiberopticbundling including both imaging and illumination fibers in a singleshaft) is advanced until its distal end reaches the distal end of theaccess catheter. Imaging may then be performed in a retrograde mannerwith the falloposcope and access catheter being drawn outwardly togetherthrough the fallopian tube while producing an image on the associatedvideo monitor. The lumen of the tubular access catheter will alsoprovide an access path for devices, such as drug delivery catheters,small instruments, and the like, for treatment of tubal lumen disease.

While such retrograde falloposcopic imaging techniques represent asignificant improvement, they still suffer from certain limitations. Inparticular, falloposcopes having both illumination and imagingfiberoptics require a minimum separation between the imaging lens at theend of the fiberoptic bundles and the tissue to be imaged.Unfortunately, the narrowly confined lumen of the fallopian tubecontracts soon after the access catheter has been withdrawn. Hence, thetubal wall often collapses in on the withdrawing falloposcope duringretrograde imaging, intruding upon the required imaging separation. Asthe tubal wall tissues come in close proximity with the imaging andillumination fiberoptics, excessive illumination light is reflected backto the imaging system, causing a partial or total "white-out" of theviewing monitor. These white-outs are a common and undesirablelimitation on the effectiveness of retrograde imaging of the fallopiantube and other narrow body lumens.

It would therefore be desirable to provide improved methods and systemsfor imaging fallopian tubes and other narrow body lumens. It would beparticularly desirable to provide improved access catheters and methodsfor their use which would reduce the incidence of white-out associatedwith the fallopian tubal wall approaching too close to the opticalviewing scope. It would further be desirable if such improved methodsand devices were compatible with and able to enhance the effectivenessof retrograde tubal imaging systems and methods.

2. Description of the Background Art

Kerin et al., Fertil. Steril., Vol. 54, pp. 390-400 (1990), and in J.Laparoendoscopic Surg., Vol. 1, pp. 47-56, have been described above.U.S. Pat. No. 4,793,326 describes an industrial endoscope having anelongated arm member to facilitate advancing separate illumination andobservation windows past the abrupt steps of piping elbow joints. U.S.Pat. No. 4,717,387 describes an intercardiac catheter having a distalballoon for positioning the catheter with respect to a body surface tobe viewed through an optical scope. U.S. Pat. No. 5,263,982 describes anendoscopic catheter having a laterally offset movable guidewire.

U.S. Pat. Nos. 5,047,848 and 4,825,259 disclose borescope havingspecialized distal tip gauges which permit optical measurements ofimaged features. U.S. Pat. No. 4,608,965 discloses an endoscopic sheathhaving a Malecott-type structure for anchoring the scope in a bodycavity.

U.S. Pat. No. 5,358,496 is representative of numerous instrumentsintended to be inserted through endoscopes. U.S. Pat. Nos. 3,866,601;4,306,566; 4,350,147; 4,846,812; 5,099,827; 5,263,928; 5,279,596;5,306,261; 5,307,814; 5,308,342; 5,385,152; are also relevant.

An exemplary falloposcopic imaging system is described in copendingapplication Ser. No. 08/027,475, the full disclosure of which isincorporated herein by reference.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a method for viewing alumenal wall of. a narrow body lumen. The method of the presentinvention comprises introducing a catheter within a body lumen andpositioning an optical viewing scope within a lumen of the catheter sothat a distal end of the scope is at a scope viewing position adjacentto a distal end of the catheter. A spacing structure affixed to thedistal end of the catheter maintains separation between the lumen walland the scope. This separation helps prevent imaging white-outconditions which would otherwise occur when the optical viewing scopeand body lumen wall are in close proximity. The lumenal wall is imagedthrough the scope while the distal end of the scope is in the scopeviewing position proximate the spacing structure. Although the spacingstructure will typically appear in the viewing monitor, blocking someportion of the lumen wall from imaging, the image quality andavailability are nonetheless substantially enhanced. Preferably, thecatheter is advanced distally of a target region of the body lumenduring the introducing step, and the catheter and scope are proximallywithdrawn while imaging through the distally oriented scope. This isgenerally referred to as "retrograde imaging."

In some embodiments, the imaging step comprises viewing the lumen wallat least in part through a cage disposed over the distal end of thescope. Alternatively, the spacing structure may comprise a guidewirewhich extends distally from the catheter, which guidewire may also berotated during introduction of the catheter to maneuver the catheterthrough a body lumen system. Alternatively, the spacing structure maycomprise a wire loop extending distally from the catheter body. Such awire loop may be expanded by advancing a proximal length of the wirerelative to the proximal end of the catheter. In this way, the size ofthe loop can be adjusted maintain separation between the body lumen walland the optical viewing position.

In another aspect, the present invention provides an improved method forviewing a target region of a fallopian tube. The method is of the typeincluding transcervically accessing the fallopian tube with the catheterand inserting an optical viewing scope within a lumen of the catheter sothat distal ends of the scope and catheter are adjacent to each other,and then retrograde imaging the fallopian tube by withdrawing the scopeand catheter together. The improvement comprises promoting axialalignment between the tubal wall and the distal end of the scope with astructure extending distally from the distal end of the catheter. Axialalignment between the distal end of the scope and the tubal wall willoptionally comprise axially rotating the catheter to engage thestructure against the tubal wall, where the structure is unsymmetricalabout an axis of the catheter lumen. Advantageously, such anunsymmetrical spacing structure can be used to selectively engage onlythat portion of the tubal wall which is necessary to avoid a white-out.The unsymmetrical spacing structure further avoids blocking of theimaging view where not required to prevent intrusion of the tubal walltoward the viewing scope.

In another aspect, a catheter for viewing a wall of a narrow body lumenaccording to the principles of the present invention comprises anelongate tubular body having a proximal end, a distal end and a centrallumen therebetween. The lumen receives a shaft of an optical viewingscope of the type including both illumination fibers and viewing fibers.The scope is received at a scope viewing position adjacent to the distalend of the body. Additionally, a spacing structure extends distally fromthe distal end, usually being fixed or coupled thereto, so as toseparate the scope viewing position from the lumen wall. Advantageously,the catheter of the present invention need only include a single axiallumen, thereby minimizing its cross-sectional size. Preferably, thespacing structure is affixed with a coupler ring which fittingly engagesthe body, the coupler ring ideally being disposed within the body lumenand having an outer diameter which is larger than a relaxed lumendiameter. In some embodiments, the spacing structure comprises a cagedisposed over the scope viewing position. The cage itself may comprise adistal extension of the body having a plurality of viewing slots, or mayalternatively comprise a separate structure attached to the distal endof the catheter.

In some embodiments of the catheter of the present invention, thespacing structure comprises a guidewire which extends distally of thebody, typically being cantilevered from the distal end of the catheterat the edge of a distal lumen opening. Ideally, the guidewire comprisesa coiled distal section and an uncoiled section between the catheter andcoil. This provides an increasing distal flexibility comparable to thatof distally tapering guidewires, but with a decrease in proximalguidewire cross-section. The flexibility of the guidewire is ideallysimilar to tapered guidewires sold under the tradenames "Traveler" and"Robust" by Conceptus, Inc. of San Carlos, Calif., the present assignee.The guidewire may thus find use in maneuvering the catheter through thebody lumen, and may also allow the catheter to be advanced while"antigrade" imaging through a scope at the scope viewing position. Suchantigrade imaging will potentially provide a means for directing thecatheter distally, and also provide a simultaneous image of the tubalwall. Alternatively, the spacing structure may comprise an expandabledistal loop actuable by advancing a proximal portion or extension of theloop relative to the proximal end of the body. This provides acontrollable separation between the lumen wall and the scope viewingposition to overcome white-out conditions as they are encountered alongthe body lumen. As a further alternative, the spacing structurecomprises one or more diagonal tips extending from the distal end of thebody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art access catheter and optical viewing scopeused for retrograde imaging of a fallopian tube.

FIG. 2 is a detail view showing the distal ends of the access catheterand optical viewing scope of FIG. 1 in close proximity to the tubalwall, which is typical of the white-out conditions encountered whenusing the access catheters of the prior art.

FIG. 3 illustrates a preferred combination of a hysteroscope, accesscatheter, and falloposcope for use in imaging a fallopian tube,according to the principles of the present invention.

FIG. 4 illustrates a preferred method for supporting the proximal end ofthe hysteroscope according to the method of the present invention,wherein the proximal end is immobilized by a support structure attachedto a table.

FIG. 5 illustrates a falloposcope which is separated from a tubal wallby an access catheter having a distal cage structure, according to theprinciples of the present invention.

FIG. 6 illustrates an alternative cage structure formed by cutting axialviewing slots in a distal extension of the catheter body.

FIG. 7 illustrates a falloposcope which is separated from a fallopiantube wall by an access catheter having a distally protruding diagonaltip, in accordance with the principles of the present invention.

FIG. 8 illustrates an access catheter having a plurality of diagonaltips extending from the distal end of the catheter body, in accordancewith the principles of the present invention.

FIGS. 9A and B illustrate an access catheter having a plurality of sideopenings and a central lumen opening which provide a balanced flow pathfor irrigation fluid to maintain separation between the falloposcope andthe tubal wall.

FIGS. 10A, B and C illustrate a preferred access catheter having adistal guidewire for maintaining axial alignment and separation betweena falloposcope and a surrounding fallopian tube.

FIGS. 11A, B, C, and D illustrate access catheters having a guidewirewhich extends from the distal end of the catheter body to form a distalloop, which distal loop can be expanded by axially advancing a proximalextension of the guidewire, in accordance with the principles of thepresent invention.

FIGS. 12A and B illustrate an access catheter having an extendeddiagonal tip formed by joining different tubes and cutting the joinedtubes along a curve.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Referring to FIGS. 1 and 2, a prior art retrograde fallopian tubeviewing system 10 includes an access catheter 12 and a falloposcope 14.Prior art viewing system 10 is inserted to the distal portion of afallopian tube 16, and is withdrawn proximally as indicated to provideretrograde imaging. Fallopian tube 16 is quite narrow and tortuous, andthe tubal wall is highly flexible. Hence, as prior art imaging system 10is withdrawn proximally, the tubal wall is distended by the access cover12, and then collapses down to its relaxed shape after a distal end 18of the access catheter has passed. As optimal imaging occurs when thedistal end of the falloposcope is substantially aligned with the distalend of the access catheter, the tubal wall often comes into closeproximity with distal end of falloposcope 20.

Falloposcope 14 generally includes two distinct types of optical fibers.The first group of optical fibers is used to transmit light to thedistal end of falloposcope 20 to provide illumination for opticalviewing. The second type of optical fiber, often comprising a singleoptical fiber bundle called a "coherent image fiber optic bundle,"transmits an optical image from a lens at a distal end of falloposcope20 to a proximal imaging apparatus. The image itself comprises theillumination light from the illumination fibers which is reflected byobjects located within a field of view 22 of distal end of falloposcope20. As the tubal wall comes into close proximity with both theillumination and optical viewing fibers at the distal end of thefalloposcope, the imaging apparatus is unable to produce a coherentpicture, and a partial or a total white-out occurs on the viewingmonitor.

A particularly preferred method and apparatus for performinghysteroscopic and falloposcopic procedures, including retrogradeimaging, is described in copending U.S. patent application Ser. No.08/207,475, the full disclosure of which is herein incorporated byreference. As more fully explained in that application, a preferredmethod for performing falloposcopic procedures makes use of ahysteroscopic viewing scope 30 having a working shaft 32 with adeflectable distal end 34, as shown in FIGS. 3 and 4. Working shaft 32is introduced to the uterus U, ideally using an adjustable supportsystem 40. Deflectable distal end 34 is directed toward an ostium 36 offallopian tube F. The uterus will be distended by introduction ofirrigation fluid so that a guidewire may be directed into the fallopiantube using visualization through hysteroscope 30. Optionally, theguidewire 42 is disposed at the distal end of a catheter, as describedhereinbelow. Alternatively, a conventional guidewire is first introducedto the fallopian tube, so that an access catheter 50 may be advancedover the guidewire in a conventional manner. Where such a conventionalguidewire is used, it must generally be removed from a central lumen ofpositioned access catheter 50 to make room for falloposcope 14.

In order to further simplify the falloposcopic procedures of the presentinvention, support structure 40 immobilizes the viewing scope 30 on atable T or other surface, once the scope has been properly positioned inthe uterus. Support structure 40 includes a plurality of arms 62 andjoints 64 which are designed to freely articulate so that a support base66 at a distal end of support structure 40 can be moved freely in spaceuntil locked into position. Preferably, the support structure is firmlysecured to a table leg L. Such systems commercially available fromsuppliers such as Lino Manfrotto & Company.

Referring now to FIG. 5, a caged access catheter 70 slidably receivesfalloposcope 14 to a scope viewing position at which falloposcope distalend 20 is adjacent to a distal end of the catheter 72. A distal cagestructure 74 surrounds distal scope end 20 to prevent the tubal wall offallopian tube 16 from coming into such close proximity with the distalend of the scope that a white-out occurs.

Distal cage 74 separates the tubal wall from the scope viewing positionby any of at least three different mechanisms. First, cage 74 preventsthe tubal wall from collapsing immediately after catheter distal end 72has passed, restraining the tubal wall in its distended position,thereby preventing encroachment of the tubal wall toward the scope.Second, distal cage 74 may reposition the entire distal portion ofaccess catheter 70 away from the tubal wall to provide the necessaryseparation. Finally, distal cage 74 promotes axial alignment of catheterdistal end 72 with the fallopian tube by providing an elongated distalmoment arm through which the access catheter and tubal wall engage eachother. This also promotes alignment between the falloposcope field ofview 22 relative to the orientation of the local fallopian tube axis.

Referring now to FIG. 6, an alternative caged access catheter 80 isformed with a simplified cage 82. Simplified cage 82 comprises acontinuation of the catheter body beyond catheter distal end 84, inwhich a plurality of viewing slots 86 have been cut. Both cagedembodiments of the present access catheter generally providesubstantially axisymmetric viewing through an open distal end of thecaged structure and through viewing slots 86, or the analogous gapsbetween the cage structural elements. Rotation of such caged accesscatheters is generally not necessary to insure separation between thefalloposcope and tubal wall, but will allow viewing of tubal wallelements which would otherwise be blocked during at least a portion ofthe scan.

Referring now to FIG. 7, a diagonal tip access catheter according to thepresent invention comprises a diagonal tip 92 extending distally fromcatheter distal end 94. It can be seen that diagonal catheter 90 must berotated so as to engage tubal wall 16 with diagonal tip 92. It can alsobe seen that the field of view 22 is clear in much of the area wheredistal structure is not required to engage the tubal wall. The angle ofdiagonal tip 92 will typically be in the range between 45° and 80° fromnormal, and need not be constant nor extend the entire catheter width. Amultiple angle access catheter 100 reduces the need for rotating thecatheter, as seen in FIG. 8.

Referring now to FIGS. 9A and B, a fluid separating catheter 110comprises a plurality of radial distal passages adjacent to the catheterdistal tip 116. Radial passages 112 direct clear flush solution againstthe tubal wall of fallopian tube 16 to promote separation betweenfalloposcope 14 and the tubal wall. Flush solution also flows out thedistal tip 116 of fluid catheter 110 around falloposcope 14, therebypromoting separation between the distal end of the falloposcope and thetubal wall. The fluidic paths represented by the radial passages 112,are preferably balanced by varying the sizes of the radial passagesrelative to the open gap 114 between the catheter and falloposcope atthe distal end.

A fixed distal guidewire access catheter 120 will be described withreference to FIGS. 10A through C. Guidewire catheter 120 comprises adistal guidewire 122 extending distally from a distal end of thecatheter body 124, typically by a distance from 0.5 to 5 cm, ideallybeing 1 to 3 cm long and less than 0.02"in diameter. The catheter bodyincludes a distal portion 126, typically being between 2.2 and 3.0 F,and first and second enlarged portions 128, 130. First and secondenlarged portions 128, 130 reduce the pressure required for theintroduction of clear flush around the falloposcope 14, as is more fullyexplained in copending U.S. patent application Ser. No. 08/207,475, thefull disclosure of which has previously been incorporated by reference.A Touhy-Borst valve 132 is provided near the proximal end of thecatheter to seal the proximal end and also allow access for falloposcope14. An irrigation port 134 is also provided.

A particularly advantageous structure for supporting distal guidewire122 comprises a distal ring coupler 125 which is fittingly insertedwithin distal portion 126 of guidewire catheter 120. The ring couplerprovides effective support for the guidewire, but does not increase theproximal size or stiffness of the catheter body, and also maintains asmooth outer surface. Typically, the coupler ring and guidewire willcomprise stainless steel, platinum, or a shape memory alloy such asNitinol™, or the like. The guidewire will typically be coiled, but willideally include an uncoiled portion extending to internal coupler ring125, thereby minimizing the blockage of the catheter lumen.

Distal guidewire 122 is offset distally at an edge of guidewire catheter120, and thereby allows the rotational engagement of the tubal walldescribed above regarding FIG. 7. Advantageously, the guidewire blocksthe smallest possible imaging area, and also provides increasedfunctionality for the catheter by allowing the catheter to beself-guided during introduction. Furthermore, the central lumen is notoccupied by a conventional guidewire during advancement of the catheterinto the fallopian tube, thereby providing the attending surgeon theoption of advancing the falloposcope to the viewing position ofguidewire catheter 120 to visually direct catheter advancement.

Referring now to FIGS. 11A through D, a looped guidewire access catheter140 generally comprises a guidewire which extends distally from a distalcatheter body end 143, the guidewire forming a distal loop 142. Aproximal extension 144 of the guidewire runs along the length of thecatheter body, allowing the distal loop to be manipulated by axiallyadvancing and retracting extension 144 relative to the proximal end ofthe catheter body. As shown in FIGS. 11B through D, extension 144 may bedisposed within the lumen of the catheter body, or may alternativelypass through guides 146 on the outer surface of the catheter.Alternatively, a separate lumen may be included in the catheter body,although this will require an increase in the cross-sectional size ofthe catheter. The guidewire may be attached to the distal end of the tipusing coupler ring 125 (FIG. 10C), or may alternatively extend from adistal outer ring 148, or from the catheter lumen wall itself.

Advantageously, distal loop 142 provides an active mechanism for thesurgeon to control the separation between the tubal wall and thefalloposcope. By advancing extension 144 distally only when a white-outcondition occurs, the distance between the tubal wall and the scope maybe varied without having to move the scope itself. The guidewire loopmay further be retracted when not in use, and may also be biased toassume a particular distal shape, as seen in FIG. 11C.

FIGS. 12A and B illustrate a particularly advantageous access catheter150 which is formed by joining an intermediate tube 151 and an end tube152 to catheter body tubing 153. The tubes may be adhesively bonded, orpreferably melted together. The durometer of the tubing increases towardthe distal end 154. A curved cut forms an extended diagonal tip 157.Proper selection of tubing materis, together with careful shaping of theextended tip 157, provides control over the flexibility of the distalstructure. Clearly, the tip shape may comprise a smooth curve or aseries of angles, and any number of tubing sections may be joined,within the scope of the present invention. Advantageously, extendeddiagonal tip 157 provides the functionality of a distal guidewire, butwith an easily fabricated, uninterrupted structure.

Although the foregoing invention has been described in some detail byway of illustration and example, for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A catheter for viewing a wall of a narrow bodylumen, the catheter comprising:an optical viewing scope includingillumination fibers and viewing fibers within a single shaft; a flexibleelongate tubular body having a proximal end, a distal end, and a centrallumen therebetween, the lumen slidably receiving the shaft of theoptical viewing scope such that the optical scope extends distally to aviewing position adjacent to the distal end of the body; and a spacingstructure, comprising a plurality of diagonal tips extending distallyfrom the distal end of the body so as to maintain separation between thescope viewing position and the lumen wall.
 2. A catheter as claimed inclaim 1, wherein the catheter body includes a single axial lumen.
 3. Acatheter as claimed in claim 1, wherein the plurality of tips haveangles between 45° and 80° from the normal to the lumen.
 4. A catheteras claimed in claim 3, wherein the diagonal tip angle of the pluralityof tips extend along the length of the tip.
 5. A catheter as claimed inclaim 3, wherein the diagonal tip angles of the plurality of tips arenot constant along the diagonal tips.
 6. A catheter for viewing a wallof a narrow body lumen in combination with an optical viewing scope ofthe type including illumination fibers and viewing fibers within asingle shaft, the catheter comprising:a flexible elongate tubular bodyhaving a proximal end, a distal end, and a central lumen therebetween,the lumen slidably receiving the shaft of the optical viewing scope to ascope viewing position adjacent to the distal end of the body; and aspacing structure extending distally from the distal end of the body soas to slidably contact the lumen wall and maintain separation betweenthe scope viewing position and the lumen wall, wherein the spacingstructure comprises a diagonal tip extending from the distal end of thebody, wherein the diagonal tip comprises a stiff material relative tothe material used to form the elongate tubular body, and an intermediatematerial disposed between the stiff material and the elongated tubularbody and wherein the diagonal tip is defined by a curve or angle.
 7. Acatheter as claimed in claim 6, wherein the diagonal tip comprises aplurality of intermediate materials.
 8. A catheter as claimed in claim6, wherein the diagonal tip has an axial flexibility and length suitablefor the diagonal tip to provide the functionality of a distal guidewire.9. A catheter as claimed in claim 6, wherein durometers of the materialsincrease toward the distal end.